Organization and visualization of data substantially affects how well that data can be understood by a user. Visual characteristics of a data display, such as spatial or chromic relationships between elements on the display, shape or size of display elements, and data display rate can all be adjusted to help a user better comprehend the displayed data in a more accurate and/or efficient manner.
One difficulty with visualizing data is that it is rarely acquired at a rate which is ideal for the user to visualize it. In most cases, increasing or decreasing the rate at which the data is displayed will provide information which is not clear from examining the data at the rate the data was acquired. If the data is displayed at a faster rate than is was originally acquired for example, long or medium term trends in the data may become visible which were not visible before. Viewing data at this faster rate also allows data acquired over a period of several hours or days to be visualized in minutes. Displaying data at a slower rate than it is acquired may allow the user to detect events which pass too quickly to see at the speed the data is acquired.
A second problem with visualization of data is that human perception and technology limitations both provide boundaries on the maximum rate visual data may be presented. For example, conscious human perception is typically limited to about 20 changes per second (termed the Persistence of Vision of the user). If the data display is updated at more than 20 times in one second, some of the changes in the data will not be detected by the user. Similarly, data may simply not be displayable at the rate of acquisition due to system limitations, such as network speed (i.e., the communication link between the source of data and the display) or the capabilities of the display itself. An update of graphics on a display sent over a network commonly exceeds the speed capable of the network. Thus, updating a display in real- time with data on the other side of a network becomes a significant communications problem.
There are currently a number of methods for displaying data at a rates other than the rate the data was acquired, or accounting for system data rate limitations. System limitations, for example, may be overcome by storing the data and playing it back later. This solution, has the obvious disadvantage that it means the user is not examining the data in real-time. For some applications real-time examination of the data is crucial. Ignoring some data is one simple method of allowing data, acquired at a rate faster than can be displayed due to system limitations, to be displayed in real-time. It has the disadvantage that ignored data is not seen by the user. Thus, this solution may not be appropriate in situations where the user is attempting to detect specific instantaneous events, or where immediate notification of a particular condition is critical.
When a user is attempting to detect long or medium-term data trends, is it very common to compress the data on the graph by packing the data points very close together without combining data points. Typically the user is limited to estimating standard deviations or major data trends using this technique. Also, this technique cannot be applied to bar graphs or other display types in which each data items writes over the previous data item from the data stream. In other words, it is not useful for display types in which time is not a dimension on the graph. Furthermore, in some instances, individual data items are not the focus of the user's attention so there is no good reason to process each data item individually for display.
Present techniques for visualizing data at a rate faster than it is acquired are furthermore not very effective for dealing with discrete data, in which particular states or transitions are most important. Accelerated displays tend to look like a blur of colors, indecipherable to the user. These accelerated displays also require more concentration, possibly reducing the number of such accelerated elements a user can effectively examine at once.